The present invention relates to rotor and stator interconnections, as in synchros of the type used in pressure sensing applications. In one such application, an oil pressure transducer is mounted directly on an aircraft jet engine. In such systems, adverse temperatures and vibrations are encountered, yet an electrical connection between a movable element (a rotor) and a fixed source of electrical rotor excitation must be maintained, while allowing limited relative rotation between rotor and stator.
Several prior art systems have been proposed for such a synchro. A sliding contact, as between a movable brush and a fixed contact ring, is used in some applications to transmit an electrical rotor excitation while allowing rotation. Such a system is acceptable in some applications, but provides contact noise (in the form of a high frequency noise signal) in response to friction resulting from relative movement. Such noise signal is undesirable in some applications. Additionally, in such systems an accurate zero-load position is difficult to obtain. Further, such systems tend to wear and require maintenance to avoid failure. The brushes, as they wear, also produce undesirable debris which can prevent proper synchro operation.
Other systems have been proposed for such contacts. However, these contacts are either difficult to manufacture, costly to assemble, involve many parts and/or very delicate parts. Many parts or delicate parts present reliability and a cost problems which are avoided if possible.
Other prior art synchros include a pair of conductors which have the possibility in some applications to short together and effectively defeat the synchro by eliminating the rotor excitation signal carried by the conductors. As such, such systems are unreliable and inaccurate and therefore undesirable.
Some other systems are possible when environmental factors (vibration and temperature) are not present.
Some synchros have also been proposed using a uniform-diameter series of stacked wire coils.
Many of the prior art synchros suffer from an undesirable hysteresis effect in the relationship between the output electrical signal and the input, the rotary position of a shaft. A synchro, ideally, not only does not have hysteresis in such relationship, but also has a constant proportion between rotary position of the input (rotor shaft) and the output signal (on the stator).
Examples of such prior art are shown in U.S. Pat. Nos. 3,976,965 and 3,295,083 and the patents cited as prior art therein.
Accordingly, the prior art systems have significant limitations and disadvantages.